The present invention relates to a motor for a pump, especially a pump for a drum, barrel, or other tanks or containers. The pump includes a preferably pressure-encased or shielded housing in which a rotor, via its rotor shaft, is rotatably mounted; a stator disposed in the housing and surrounding the rotor; and a power supply line that is connected to a switch or control device.
Such pump motors are conventionally embodied as commutator motors. The problem with such motors is that deposits of carbon dust form in the motor housing over time. This is especially the case with closed, pressure-encased housings Undesired current leakage can then occur. This can lead to the formation of sparks. If such a pump is operated in explosion-prone areas, explosions can occur due to this spark formation. Since the formation of sparks occurs only if these commutator motors are not properly operated, a potential equalization is directed to be undertaken on the pump motors in order to prevent the harmful formation of sparks. However, such a potential equalization is frequently not undertaken either for reasons of convenience or oversight.
For this reason, pump motors have been developed with which the danger of explosions is to a large extent precluded, even where the motor is not operated properly. With these motors, the explosion-proof, pressure-encased pump motor is double insulated, with the metallic motor housing being surrounded by plastic installation. However, even with these motors, leakage currents can still occur due to the presence of carbon dust deposits in the interior of the housing. The known commutator motors furthermore have the drawback that the brushes and commutators wear out. The service life of such motors is therefore relatively short, being of the order of magnitude of approximately 500 operating hours.
It is an object of the present invention to provide a motor of the aforementioned general type that can be operated without danger even where the motor is not operated properly, and that has practically no parts that are subject to wear, so that the motor has a very long service life and is very economical to manufacture.